Nicholas Piggin <npig...@gmail.com> writes:
> Radix guest support will be removed from the P7/8 path, so disallow
> dependent threads mode on P9.
>
> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
> ---
> arch/powerpc/include/asm/kvm_host.h | 1 -
> arch/powerpc/kvm/book3s_hv.c | 27 +++++----------------------
> 2 files changed, 5 insertions(+), 23 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_host.h
> b/arch/powerpc/include/asm/kvm_host.h
> index 05fb00d37609..dd017dfa4e65 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -304,7 +304,6 @@ struct kvm_arch {
> u8 fwnmi_enabled;
> u8 secure_guest;
> u8 svm_enabled;
> - bool threads_indep;
> bool nested_enable;
> bool dawr1_enabled;
> pgd_t *pgtable;
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index cb428e2f7140..928ed8180d9d 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -103,13 +103,9 @@ static int target_smt_mode;
> module_param(target_smt_mode, int, 0644);
> MODULE_PARM_DESC(target_smt_mode, "Target threads per core (0 = max)");
>
> -static bool indep_threads_mode = true;
> -module_param(indep_threads_mode, bool, S_IRUGO | S_IWUSR);
> -MODULE_PARM_DESC(indep_threads_mode, "Independent-threads mode (only on
> POWER9)");
> -
> static bool one_vm_per_core;
> module_param(one_vm_per_core, bool, S_IRUGO | S_IWUSR);
> -MODULE_PARM_DESC(one_vm_per_core, "Only run vCPUs from the same VM on a core
> (requires indep_threads_mode=N)");
> +MODULE_PARM_DESC(one_vm_per_core, "Only run vCPUs from the same VM on a core
> (requires POWER8 or older)");
Isn't this also a security feature, where there was an ask to make sure
threads/vCPU from other VM won't run on this core? In that context isn't
this applicable also for P9?
>
> #ifdef CONFIG_KVM_XICS
> static const struct kernel_param_ops module_param_ops = {
> @@ -2227,7 +2223,7 @@ static int kvmppc_set_one_reg_hv(struct kvm_vcpu *vcpu,
> u64 id,
> */
> static int threads_per_vcore(struct kvm *kvm)
> {
> - if (kvm->arch.threads_indep)
> + if (cpu_has_feature(CPU_FTR_ARCH_300))
> return 1;
> return threads_per_subcore;
> }
> @@ -4319,7 +4315,7 @@ static int kvmppc_vcpu_run_hv(struct kvm_vcpu *vcpu)
> vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST;
>
> do {
> - if (kvm->arch.threads_indep && kvm_is_radix(kvm))
> + if (kvm_is_radix(kvm))
> r = kvmhv_run_single_vcpu(vcpu, ~(u64)0,
> vcpu->arch.vcore->lpcr);
> else
> @@ -4934,21 +4930,8 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm)
> /*
> * Track that we now have a HV mode VM active. This blocks secondary
> * CPU threads from coming online.
> - * On POWER9, we only need to do this if the "indep_threads_mode"
> - * module parameter has been set to N.
> */
> - if (cpu_has_feature(CPU_FTR_ARCH_300)) {
> - if (!indep_threads_mode && !cpu_has_feature(CPU_FTR_HVMODE)) {
> - pr_warn("KVM: Ignoring indep_threads_mode=N in nested
> hypervisor\n");
> - kvm->arch.threads_indep = true;
> - } else if (!indep_threads_mode &&
> cpu_has_feature(CPU_FTR_P9_RADIX_PREFETCH_BUG)) {
> - pr_warn("KVM: Ignoring indep_threads_mode=N on
> pre-DD2.2 POWER9\n");
> - kvm->arch.threads_indep = true;
> - } else {
> - kvm->arch.threads_indep = indep_threads_mode;
> - }
> - }
> - if (!kvm->arch.threads_indep)
> + if (!cpu_has_feature(CPU_FTR_ARCH_300))
> kvm_hv_vm_activated();
>
> /*
> @@ -4989,7 +4972,7 @@ static void kvmppc_core_destroy_vm_hv(struct kvm *kvm)
> {
> debugfs_remove_recursive(kvm->arch.debugfs_dir);
>
> - if (!kvm->arch.threads_indep)
> + if (!cpu_has_feature(CPU_FTR_ARCH_300))
> kvm_hv_vm_deactivated();
>
> kvmppc_free_vcores(kvm);
> --
> 2.23.0
